Yeah. Experiencing high CPU usage here as well. I've had to lower the voice count to 7 or even 6 in some cases, and also increased the buffer size in my ASIO4All driver.
It's my understanding, based on a lot of reading here, as well as reviews of Arturia's products over the years, that their newly-released synths have a history of cranking on CPUs at first, but subsequent updates HUGELY fixing that.
And Matrix 12 is one of their newest, eh. I've also seen the Vox have some pretty high CPU usage.
As such, I'm guessing they're aware of and working on it. They just keep it to themselves, apparently. .. Ditto regarding resizeable GUI.
Interestingly, I haven't noticed any such skipping when playing Matrix 12 presets in Analog Lab ......
Anyhow, just adding my "me too" to the CPU load problem with Matrix 12
SYSTEM:
Win 7 Pro 32-bit
Dell Optiplex GX620 (modified)
Pentium D dual-core 3.4Ghz
3Gb DDR2 RAM
Nvidia GeForce GTX560 Ti w/1Gb VRAM
Soundmax Integrated Digital Audio
several hard drives